With increasing advance of information technologies, the general trends in designing electronic devices are toward small size, light weightiness and easy portability. For example, after smart phones and tablet computers are introduced into the market, the smart phones and the tablet computers are gradually used to connect to the internet or browse data in order to replace the heavy and bulky notebook computers. Nowadays, the smart phones or the tablet computers are widely used to browse data, watch image data, execute application software or make a call. However, due to the size limitation of the smart phone or the tablet computer, the size of the display panel of the smart phone or the tablet computer is gradually reduced. Consequently, only small amount of messages can be simultaneously shown on the display panel.
Recently, a smart phone or a tablet computer with a flexible display panel is introduced into the market. The applications of the flexible display panel are no longer restricted by the rigidity of the conventional display panel. After the flexible display panel of the smart phone or the tablet computer is unfolded, more messages can be simultaneously shown on the flexible display panel. Consequently, the electronic device with the flexible display panel has small volume and large display area.
As known, the bent region of the flexible display panel is frequently used. Consequently, the image on the bent region of the flexible display panel is readily suffered from distortion. Under this circumstance, the image quality is unsatisfied.
Generally, the bending curvature, the bending frequency and other parameters are widely used for evaluating the conditions of the bent region of the flexible display panel. The bending curvature and the bending frequency may be acquired by a variety of bend sensors.
Conventionally, the bend sensors are disposed on a backside of the flexible display panel. The bend sensors include for example fiber-optic bend sensors, infrared bend sensors, force-feedback bend sensors or piezoelectric bend sensors. In views of cost-effectiveness and applications, the piezoelectric bend sensors are the most popular.
Generally, the resistance value of the piezoelectric bend sensor is changed according to the magnitude of the stress applied to the piezoelectric bend sensor, and the bending degree of the flexible display panel is correspondingly determined. Since the contact stress of the piezoelectric bend sensor is non-uniform and non-directional and the piezoelectric bend sensor is opaque, it is difficult to integrate the piezoelectric bend sensor into the flexible display panel and the applications of the flexible display panel are restricted.
Therefore, there is a need of providing an improved bend sensor and an improved bend sensing method in order to overcome the above drawbacks.